Sans little sister
by MonkeyGirl13
Summary: Gaster has to create a weapon not a little sister for Sans and Papyrus. What happens when a science experiment goes wrong and what will the consequences be? please read and review.
1. Chapter 1

**I do not Undertale only my OC**

Gaster sat in his lab it was late again he had stayed back again he had got Sans, his eldest son, to watch over Papyrus, his youngest. Gaster had been recently given the job, by the king mainly, to create a weapon of any kind to protect the monsters and to collect the souls from any fallen humans. Groaning in annoyance Gaster stood up and grabbed his mug and filled it with coffee and waked back to his designs all with red corrections scribbled over them. He glanced at the clock as he passed it. 3:30am. He sighed he never stayed this long but he knew he couldn't fail the king that was when a idea hit him looking over at the wal he saw a bone that was lodged in rembering that Sans had been training with Gaster earlyier the latter pulled the bone out and inspected it. One end was alright and the other was now jagged and sharp but this could still be used. Gaster placed the bone in a large tube and placed electrodes on it and pressing several buttons filling the tube with a jelly like water. He then clicked a red button which created a blinding white light making him cover his eyes with his lab coat. After the light subsided Gaster looked inside the tube instead of a useless bone now floating in the tube was a small skeleton child looking at it closer Gaster concluded that it was a girl who must of been just about 5 years old. She had a small face with no jaw maybe from the broken part of the bone it still had teeth but were still childrens teeth. She was very small indeed smaller than Sans and even he was small for a skeleton. Gaster stared in shock for several minutes before deciding to test if his theory waas correct pressing several buttons the skeleton girl was shocked several times and after the eigth time the girl became angered that she had, had enough her left eye became englufed in a blood red flame and as did her hand. What happened next shocked Gaster and pained the child the skeeton shook in pain as she changed her head turned into a gaster blaster her teeth becoming jagged with it her body then morphed into a dinosaur like stance her legs were longer and her claws were sharper. Her spine had elongated and three bones became larger as well. As well as that she grew a tail that twisted and wrighted in pain until the transformation was complete she looked at the burry figure that was Gaster and opened her new mouth firing a large red blast cracking the glass. When Gaster thought that she would break the glass her eyes dimmed down and soon she turned back to her normal skeleton form. Hesitantly Gaster opened the tube and grabbed a towel picking up the child. He then dried her and thats when another surprise happend fire grew from the top of her in the shape of hair it was red like her eye and went to her shoulders were it then flicked up. Little pieces of it would go up and detach from the hair and evaporate in the air. Gaster smiled at the small child feeling like he had just been blessed with another child but his smile went away when he realised what she was created for and that he wuld have to show her to King Asgore and Queen Toriel tommrow when he would have to tell them about her. But for now he had a child to take care of he felt almost lucky that the most recent to perish was a young girl. He placed the skeleton child in a small outfit which consisted of a red knee high length dress with a black bow wrapped around the waist. He then noticed that she was waking up after a few mumbles she looked at Gaster.

"w-w-who are you?" The timid child asked this made Gaster feel worse about tommorow she sounded so innocent and the king would be forcing her to kill to be of use to him.

"My name is Gaster but you can call me your 'dad'" The young skeleton looked down before smiling. Gaster then placed a finger to his chin before saying."now you still need a name... how about Scarlet?" This made Scarlet smile even more and nod. "okay then now let's get you home Scarlet" Scarlet allowed Gaster to pick her up and carry her to the entrance where she began to fall asleep looking even more inoccent and cute which made the feeling in Gaster feel even worse. But what made him worry even more was having to tell Sans the situation Papyrus was still young enough to have a large amount of innocence and naivty but Sans was definietly special. Gaster knew he wouldn't be able to lie to Sans and the truth would make Sans protective over Scarlet which could endanger them both. But for now Gaster had to get Scarlet home he could worry about telling his eldest son the truth when he got home.


	2. Chapter 2

When Gaster arrived a few hours later he didn't expected Sans AND Papyrus to still be awake and watching Tv, closing the door behind him Gaster made his presence known by letting out a small cough.

"DADDY YOUR HOME!" Papyrus jumped off the sofa and ran to his fathers side and jumping up and down grabbing his lab coat.

"Papyrus what are you still doing up?" Sans at this point had gotten off of the sofa and stood behind his younger brother.

"He wanted to wait up for ya he insited on it" Gaster saw Sans and rembered why he was nervous to get home. "hey what ya got there dad?" That was when Sans pointed at the sleeping form of Scarlet.

"This is your new sister" He then places her in front of the two whilst kneeling down. "Her name is Scarlet" at this point Scarlet was waking up she began rubbing her eyes as she looked around Sans was looking at his father questioningly.

"hey dad can I have a word with ya?" Gaster swollowed a dry lump in his throat and stood up to follow Sans into the kitchen.

"Papyrus can you watch your little sister whilst Sans and I talk in the kitchen?" Papyrus nodded eagerly.

"OF COURSE I CAN I WILL BE THE BEST SISTER WATCHER" Gaster smiled and walked into the kitchen with Sans where the latter shut the door.

"so why did you create her then?" Gaster sighed.

"to be honest with you Sans I was trying to make a weapon for the king to gather more souls" Sans glared at his father.

"so what ya just gonna let them use her as a weapon? How could she even be used as a weapon she only has 1 LV?" Gaster looked away.

"its because she has your powers but much more agressiveness that your other side has" Sans glared at his father.

"WHAT! you gave her my side and you made it MORE AGRESSIVE?!" Gaster moved back slightly Sans sighed and calmed down. "So when are ya gonna have to bring her in?" Gaster sighed.

"Tommorow morning you can come if you like" Sans sighed.

"no I can't do that I can't see my little sister used as a weapon" Gaster looked down ashamed.

"I understand I truly didn't mean to create her for this life" Sans could only sigh as he walked away. Gaster followed after him to see both Scarlet and Papyrus cuddled next to each other on the sofa fast asleep.

"I'll put them to bed, Scarlet can sleep with me tonight" Sans teletported to Papyrus's room both Gaster could argue. After tucking him in he teleported to his room with Scarlet. He grabbed a spare blanket and placed Scarlet on his bed laying down next to her he placed the blanket over her and as he turned over he whispered. "goodnight lil' sis I hope I'll see ya in the morning".


	3. Chapter 3

The next morning when Sans woke up he looked to the side where Scarlet was gone sitting up he looked around and not finding a trace of her he got up and ran downstairs. He found Scarlet sitting on the sofa watching Tv with Papyrus letting a sigh of releif he went to Scarlet.

"hey there sis what ya doing up so early?" Scarlet looked up at him.

"dad came and woke me up he said I had to go and meet the king and queen this morning" Sans looked worriedly at his sister but she didn't seem to notice. At this point Gaster walked into the room seeing Sans but he looked away.

"come along Scarlet we need to set off now" Scarlet nodded and hugged both of her brothers Sans shocked at first but returning the gesture Sans watched as Scarlet grabbed Gaster's hand and walked out of the door. Sans looked down and sighed muttering to himself.

'I must be insane' sighing Sans turned to his brother and said. "hey bro I'm gonna go and make sure that dad and Scarlet get there okay. Do you think you can sit and watch the Tv until we return" Papyrus nodded.

"OKAY GOODBYE BROTHER" Sans watched Papyrus sit on the sofa and turn on the Tv. He teleported to the throne room where he hid behind a pillar out of veiw of the three guards in the room. In front of him was Gaster still holding Scarlet's hand who was now seeming more timid in front of Asgore and Toriel, Asgore stood up followed by Toriel he looked at Scarlet before saying.

"so you must be the one that Dr. Gaster was talking about" He looked at Scarlet. "I guess that when she is trained she will be able to kill many unwanted humans" This made Scarlet become untimid.

"what? I don't want to hurt anyone" this made every monster in the room look at her in shock except for Asgore and Toriel. Toriel seemed almost glad to hear this being against the idea of a weapon to hunt down humans but Asgore was angry.

"I beg your padon? You were created to kill humans and bring me their souls. This is your only purpose in life" He got angrier and angrier until he was shouting. "And if you will not do so you are no use to us" Scarlet looked at the monster king now no fear was in her if anything there was anger.

"But why? why must my only reason to live be killing humans?" ' _she has a good point_ ' Sans thought to himself. "Why can't we just talk to the humans and tell them what's going on. Or better yet why don't we try to befriend them?" This seemed to have struck a nerve in the king and as Scarlet walked forward away from Gaster he looked down.

"If you think that we should help the humans then you truly are no use to us" His face seemed to darken for a second before a large red spear was summond from thin air Scarlet's eyes widened as she went to back away only managing to trip over her feet landing on her back. Sans saw that Asgore was going to swing at Scarlet so he teleported and held his sister close as the blades got closer. Both Sans and Scarlet closed their eyes expecting to die when no hit arrived they opened their eyes to see a green dome over them. Looking back Sans saw Gaster holding his hand towards the two Toriel got out of her shocked state and pushed past Asgore to the two children. Gaster removed the dome as Toriel kneeled next to the children.

"oh my goodness are you two alright my children?" Sans looked up at Toriel.

"yes thank you your highness. Right sis?" But Scarlet was in a state of shock but inside her mind angry thoughts were bubbling. ' _he tried to kill me- no he tried to kill me and Sans, my big brother. My only big brother_ ' By now Scarlet had a scowl growing on her face and Sans knew there was no calming her down at this point. "your highness we need to get back right now" A painful scream came out of Scarlet as she held her head in pain fire bursting out of her eye her transformation then began and after a few seconds a transformed Scarlet let out a roar that cracked the windows. Sans teleported himself and Toriel next to Gaster. "uhhh dad how do we turn Scarlet back?" Gaster glanced at Sans.

"the only way is to weaken her we have to attack her make sure she is weak enough then she will collapse and turn back" Gaster and Sans ran to Scarlet as she prepared a blast at the terrified guards Gaster fired a beam of blue rope like object. The beam wrapped around her snout clamping it shut making her struggle. Scarlet then threw her head around causing the binding's to break she then turned to Gaster growling but before she could attack Sans fired several bones at her one managing to cut her and a neon blue liquid fell from her cheek.

"sorry sis but this is the only way" Whilst Scarlet wasn't looking Gaster fired a gaster blaster at her this shocked Scarlet who open fired at the blast avoiding damage but got pushed back. Using so much energy already Scarlet was already to pant in exhaustion Gaster looked to Sans.

"Sans one more hit should tire her out" Sans nodded and looked at Scarlet before firing a bone at her the bone smashed a rib and made her scream in pain staggering backwards. Scarlet then fell to the floor and changed back she was on her hands and knees and was panting exhausted from the fight. Sans ran to her and picked her up hugging her close looking at her she still had a cut on her cheek and her rib remained broken. Asgore walked foreward and Sans held Scarlet closer.

"So that is the true extent of her power?" he asked Sans glared but Gaster answered/

"yes but they are highly volatile she can't control them" Asgore looked down and the room went silent until Toriel gained her senses.

"why on earth did you attack her? she was doing no wrong yet you attacked her" Toriel advanced on him before turning back to Gaster. "I think it would only be wise to let her life a normal life with her family and **not** used as a weapon" Sans smiled at this looking at his asleep sister. "but she will still need to be taught how to control her other side" at this Sans spoke up.

"don't worry your highness I can help her control it" Toriel smiled at Sans and then they were sent away.


	4. Chapter 4

A year has gone by and Scarlet can still not control her other side that she named her 'wild side'. She hated the fact she had this side but always went with either Sans or Gaster to train to control it. However after the castle incident all of the monster children her age had begun to bully her. She never told her family in case they did something reckless but on this day as school ended Scarlet got up and set off but as she exited the school three bully's saw her.

"hey stop right there freak!" this made Scarlet run she ran into the woods near the river where Sans and her found a great area to train where they had placed barrels which they usd to attack. Scarlet hid behind one of the barrels hoping that they wouldn't find her. "Come out freak. Come on we promise that if you come out we will be gentle this time. One of the kids agreed.

"yeah this time we won't leave you with a black eye" the other monster in the group laughed joking.

"don't you mean black eye socket?" The three laughed and continued their search Scarlet's hair had dimmed down by now and fire red tears were falling from her eyes as she quietly dialled San's number.

"hey sis ya need me to pick ya up from school?" Sans asked.

"Sans I need your help some kids have been bulling me they've chased me to our training area. They're gonna hurt me Sans" Scarlet heard silence over the phone.

"Scarlet stay right where ya are. I'm coming right now" with that the call ended and Scarlet was stuck sitting behind a barrel. Suddenly a pair of hands grabbed her shoulders pushing her to the ground. Scarlet fell face first into the snow and began to cry even more.

"guys what do you think we should do to the flaming freak?" The others looked at him shrugging. "the ony way you truly put out a flame put it in water" the three smiled at each other before two of them grabbed Scarlet's wrists and ankles and carried her over to the river. The other one looked at Scarlet laughed and yelled.

"throw her!" In one swift movment Scarlet had been thrown into the frezzing river her hair extinguised instantly. Swiming to the top Scarlet spultered and coughed up water. As she swam to the riverside a foot stood on her hand looking up the boys were grinning like chesiercats. "I think we should make sure you learn some manners freak" a sound of the wind was heard before a deep voice spoke up.

"the only one who needs to know some manners is you three" The boys spun around to see Sans his eye inflamed. "so you are the three bulling my little sister? well then that's gonna right now" One of the bravest of the boys spoke up.

"or what?" Sans looked down before looking back at them his eyes gone and he was glaring at them.

"or ya gonna have a bad time" This made the boys shake with fear. "now get outta here!" The boys ran as fast as they could and as soon as they were gone Sans used his powers to lift Scarlet out of the river and onto the snow. Taking off his jacket he wrapped it around and hugging her close trying to warm her up. "there ya go sis they won't be bothering you any more" Scarlet hugged to Sans crying into his jacket Sans rubbed her back trying to warm her up and to comfort her. "come on lets get ya home dad's gonna take us to Grillby's tonight" This perked Scarlet up as she stood up she always found Grillby's a fun place to hang out the food was lovely and Grillby was funny only certain people could slightly understand him but because Scarlet was made partly of fire she seemed to understand everything he said perfectly.

 **Scarlet's P.O.V**

Sans teleported to our house and dried me off with a towl later that night we went to Grillbys and sat down. By the end of the meal Papyrus was already asleep due to the fact that greasy food always but him to sleep. Gater turned to Sans and me looking once at Papyrus.

"my children there is a reason why I wanted to eat out tonight. I have two pieces of amazing news. Firstly Scarlet I want you to have this" he pulled out a strange device that could only look like a dog collar.

"it's a dog collar?"I asked whilst holding it in my hands.

"well actually its something that will help with your changes if you transform at random times or when you can't control it after purposefully doing so it will send some shocks through your system which will give anyone enough time to stop you" I turned to Sans and passed him the collar and turned around whilst he placed it on. It wasn't that bad once it was on it wasnt very heavy and I couldn't feel it so I was now intrested in the next bit of news. "Next I have finally finished my finest invention yet it will give us the means to travel into different dimensions maybe different voids" we looked at dad in amazment Sans asking.

"when are ya gonna test it?" Dad answered almost as excited as us.

"tommorow morning then if it works we might be showing it to king Asgore" ugh that name always made me annoyed he was still a thorn in my side if it wasn't for him I might not have to worry about bullys.

"can we come and see it working?" Sans asked eagerly.

"if you wish but you need to bring Papyrus along as well"

"done" Sans said instently I looked up from my plate.

"Dad is it safe to test this? What if you get hurt?" Dad looked at me and Sans gave me a sideways hug.

"Don't worry Scarlet I have looked at every possible outcome that could go wrong and have worked to make sure that it is perfectly safe. You shall see it tommorow" Something told me that there might be one possibility that dad hadn't factored in and tommorow I would be proved right.


	5. Chapter 5

Scarlet woke up early that morning she went downstairs and saw that Sans was on the sofa, resting his head on his fist when Scarlet got to the bottom of the stairs he noticed she was there.

"oh heya sis I didn't think ya would be up this early" She looked down to the floor and rubbed her arm.

"I couldn't sleep" Sans smiled and patted the place next to him.

"come here" She climbd up next to Sans and leaned her head against his side as he wrapped his arm around her. "What's the matter sis?" She looked away from Sans.

"I'm worried about dad's experiment today" Sans looked worridly at Scarlet.

"don't worry sis dad's thought everything through he'll be fine" Scarlet sighed and closed her eyes. Later that day Scarlet and Sans went to the lab with Gaster many of the scientists looking at Scarlet in horror or anger. Sans placed a protective hand on her shoulder and glared at the scientists Scarlet looked down ashamed.

"they have the right to look at me like that I have got the wild side" Sans looked at his sister in shock.

"that doesn't give them the right to look at you like that" Scarlet sighed and looked down at floor. "so dad where's the invention you were talking about?" Gaster looked towards a large metal door and swiped a keycard down.

"Here it is" It was a large silver cylinder with a large switch on the side. "When I flip the switch a doorway to another world will open up and we will be able to travel to wherever it opens up". Gaster flipped the switch and a large black portal opened suddenly the machine began to spark and let out a noise that was almost animalistic. Sans grabbed Scarlet protechtively and held her close in case they needed to run. Looking at his father in worry he asked.

"Dad what's wrong with the machine?" Gaster looked back at his scared children.

"I don't know..." After presssing several buttons Gaster gasped. "oh God the machine is gonna explode and it's gonna take out the entire lab" Sans ran to the console.

"there has to be a way to minimise the blast radius" Gaster sighed.

"There is but it has to be done with manual power" tears began to well up in Sans' eyes.

"No you can't do that that's suicide!" Scarlet looked worridly at her father.

"I don't care as long as you two and Papyrus are safe" Sans glared up at Gaster.

"we are not leaving you here!" Gaster sighed sadly.

"Yes you are" Suddenly Sans and Scarlet were lifted in the air and flung backwards Sans hit the wall and quickly caught Scarlet. They stood up and ran to Gaster but a large metal door blocked their path. The duo ran to the large window and slammed their fists into the glass.

"Dad get out of there!"

"Please don't leave us dad!" Gaster sighed and as a lone green tear fell down his face he pressed a large yellow button and a large white light filled the room. When the light dissapeared Sans and Scarlet gasped the machine was destroyed and Gaster was gone. Rushing inside they found nothing but a part of his labcoat that had been ripped off. Scarlet clung to it as red tears fell like a waterfall Sans let only a few tears fall so he seemed brave. Standing up Sans placed a combferting hand on her shoulder.

"Don't worry Scarlet we are gonna fix this machine and we will get dad back I promise" Scarlet sniffled.

"Don't make promises you can't keep"


	6. Chapter 6

Sans had been working on the machine for a year now Scarlet was now a 7 year old skeleton Sans had worked every waking moment to make his father's machine work. On this day Scarlet awoke at three in the morning to the sound of someone working rubbing her eyes she got up and walked to the source of the noise. At the back of the house was a lab that only herself, Sans and Gaster knew about opening the door she saw Sans working on the machine she yawned and said.

"Sans, what are you doing? It's three in the morning" Sans looked up from his work and saw Scarlet. "you know you need to sleep as well, right?" Sans sighed as he looked at the machine. Scarlet walked up to Sans and placed a hand on his shoulder. "Sans, you know I want dad back as much as you do but I don't want to lose you" Sans looked up at Scarlet who was now close to tears, he smiled reasuringly and stood up.

"Okay, okay sis I'll go back to bed if it makes you feel better" Scarlet smiled and grabbed Sans' hand leading him back into the house and went back to bed. The next morning Scarlet woke up at ten in the morning and went downstairs for breakfast. Afterwitch she went upstairs to get dressed, Scarlet came back downstairs wearing her usual outfit. She wore a black, thick jacket with white fur (similar to Sans') with a pair of black pants. She went to the door waving to both her brothers.

"'Kay guys I'm going out for a bit I'll see ya later" Scarlet walked into the wilderness for a few minutes her hands in her pockets until she heard a small high pitched voice.

"Howdey I'm Flowey, Flowey the flower" Scarlet looks down and sees a small golden flower at her feet which was now staring back up at her.

"well hey there little guy my names Scarlet" Flowey giggles.

"I already know your name, Scarlet" Scarlet's eyes widen.

"How would you know my name?"

"I know everything about you especially that your the sister of that smiling trashbag you call Sans" Scarlet glared her eye becoming red.

"Don't you dare call my brother trashbag or you'll regret it you little weed" Flowey giggles even more.

"you are definetly your brother's sister that's even the name he gives me" a dark expression grows on Flowey's face. "but enough comparing time for the reason I came here" Suddenly several vines shot out towards Scarlet which she dodged. "Your soul is very powerful more powerful then any other monsters I've seen. With that power I might just be able to go back to my normal form" Scarlet became scared and after several attacks he shot several pellets towards Scarlet most of them missed but as Scarlet turned around one of them smashed into her tooth destroying it and cracking up her skull. Scarlet screamed in pain and fell to the floor clutching her head. "I didn't think that, that pellet would do that much damage but I'm glad it did" vines began to encircle Scarlet who now had tears of pain running down her face. Suddenly as the vines pounced a gaster blaster appeard and destroyed them Sans then stood next to Scarlet and glowed his eye blue.

"I suggest if you want to walk away from this you leave. Now" Flowey glared at Sans but left anway Sans went to Scarlet and picked her up taking her back to the secret lab. He placed her on a table and looked at the injurys. "It's not to bad I can fix it but he has managed to destroy your entire tooth. If I heal it, it will look a bit silly but if you want I can make you a gold tooth" Scarlet decided on the gold tooth and after it was placed in and she was healed she looked in the mirror. Her gold tooth glinted as the light reflected off of it from the mirror. "now we can't tell Papyrus about what has happened so we will just tell him that you fell down and hit your head on a rock" Scarlet nodded she hated lying to her brother but if he knew about Flowey then he would go after him and he might get hurt himself.


	7. Chapter 7

On this day Scarlet woke up and went downstairs to do her normal day but something felt off she felt as if she had done this before as if she was reliving a moment she had already lived. Looking around she looked for Sans maybe he was feeling the same or maybe she had eaten something from the other night that made her feel sick. When she couldn't find him she went outside to see a small kid wearing a bow in their hair and in front of them was Sans, who's eye was blue and Scarlet knew that when his eye was alight then something isn't right. Scarlet quickly hid behind a tree and watched from a distance as she listened to their conversation.

"So your the one who's been creating the time anomalies? I felt like the timeline had been reset" Scarlet became intrigued by this. "But that doesn't matter now does it? You dirty brother killer" It was only then that Scarlet noticed that the human was holding a knife and a pile of dust with a piece of red fabric in. Scarlet gasped quietly as she connected everything then Sans picked up the human and threw them into a pile of bones but before they were impaled they managed to stab into the ground stopping them from hitting the bones. The human then charged towards Sans but as they slashed Sans teleported to the side avoiding the hit but as Sans reappeared the kid's eye's glinted red before slashing him across the chest.

"SANS!" Scarlet yelled making the two look at her Scarlet threw the human into a tree running towards Sans she slid across the snow to his side. Red tears were now falling from Scarlet's eyes as she hugged Sans the blood from his jacket was now staining her hands. Sans placed a hand on her shoulder as he gasped out.

"Please don't do anything stupid" Then he turned to dust leaving Scarlet hugging onto his jacket crying into the material she looked at the pile next to her and pulled out the red fabric, which was actually Papyrus's scarf. Scarlet hugged the jacket and the scarf crying then she looked up to see the human was now getting up she glared at the human as they rubbed their head. She placed the jacket on and wrapped the scarf around her neck and put the hood over her head.

"my brother was giving you a bad time. But I am going to have a great time!" Scarlet then threw her hand forward sending forward two gaster blaster firing them at the human. They dodged the hits but Scarlet managed to hit them with a bone that stabbed into their shoulder. The human ran and tried the same trick with Sans but Scarlet grabbed their wrist. Glowing her eye she could see the terror in their eyes but she knew that she couldn't let them get past her otherwise they could kill them all. Suddenly a pain slashed through her chest looking down neon blue blood dripped from the slash mark she looked up and saw that the human was smiling at her devilishly. Scarlet stumbled back in pain and turned around to see how badly the wound was when she felt the knife slash her back, looking back she saw that the humans knife now had her blue blood on it. Scarlet gulped and fell to her knees looking up she saw the human their eyes covered in a shadow only their teeth could be seen in the daylight. The human then grabbed her by her neck and placed the knife to her head Scarlet's eyes widened in terror as the human stabbed into the centre of her forehead. Scarlet was covered in a blinding light covering her eyes she saw that she was in a barren land that was all white in front of her was a barrier that looked like what Papyrus had made.

"Didn't I tell you not to do anything stupid?" Spinning around Scarlet saw a healthy Sans standing in front of her. Not even thinking she ran into Sans wrapping her arms around him crying even more. "Hey don't worry, it's okay, your okay" Scarlet's crying subsided.

"Does that mean I died?" Sans gave her a comforting smile.

"I'm afraid so but don't worry some one else is here as well" Sans turned Scarlet around and she saw Papyrus she ran up to him and he picked her up hugging her tightly as he said.

"SCARLET I WAS SO WORRIED ABOUT YOU, WHEN I HEARD ABOUT THE HUMAN I WANTED TO CAPTURE THEM BUT THEN I FOUND OUT THAT THEY WERE NOT THAT NICE" he looked down and carried on. "SANS SAW AS THE HUMAN HIT ME AND BY MY GUESS HE FOUGHT THEM BUT I GUESS THEY GOT TO YOU TO" Scarlet wiped her tears away and smiled at him. "BUT THAT DOESN'T MATTER NOW, BECAUSE WE ARE ALL TOGETHER NOW" Sans was now standing next to them Papyrus placed Scarlet on his shoulders and they passed through the barrier.

As the light washed away Scarlet woke up back in her bed she sat up confused she looked at the alarm clock and saw that it was a few hours since her and her familys death. She didn't wait a minute before running to Sans room seeing his sleeping form on the bed she jumped on him crying in relief waking him up.

"Hey there kiddo what's up?" Scarlet then told him everything she knew. "This is amazing Scarlet this means that you can remember the timelines like me. Finally there is someone else that knows about the resets. You have no idea how long I have known about the resets and not been able to talk to someone abut them" Scarlet hugged Sans and he returned the gesture.

"Well don't worry Sans I'm always gonna be hear to talk to"


	8. Chapter 8

One year has passed and Scarlet had grown acustomed to her gold tooth if anything she had begun to love her golden tooth. On this day Scarlet woke up and got dressed ready to leave the house and go with Sans to their sentry post, as usual Sans was late getting up so Scarlet left a note and went early. She walked over the bridge that Papyrus had built she then decided to explore the woods for some reason Scarlet felt something was different today nervously fiddling with her collar. From behind her she heard the sound of snow being crunched under feet spinning around she noticed a figure behind some trees wearing a purple and blue striped jumper. Scarlet teleported behind some trees and looked at the figure more closely in front of her was a young human child the same age as Scarlet. The girl had the purple and blue jumper with a pair of black shorts she was very pale and had a few plasters on thier legs. Scarlet was confused on what to do, Papyrus had always told her that he wanted to capture a human but this was her first time to meet a real human. Deciding against what her brother would want she pulled up her hood so her face would be shadowed and teleported a few feet away from the kid.

"hey human stop" The human turned around slowly their face in a scared expression Scarlet walked up to the girl and put out her hand. "The name's Scarlet. What's yours?" The girl shuck the skeletons hand and replied.

"F-Frisk" Scarlet smiled kindly at Frisk.

"Don't worry Frisk I won't hurt ya I just wanted to talk. You see your the first human I've ever met and I kinda wanted to get to know ya" She smiled and nodded.

"okay but is it okay if we sit down for a moment I'm kinda tired" Scarlet nodded.

"Sure follow me" they found a old fallen tree with no snow on sitting down Scarlet noticed that Frisk was shivering. "You cold there, Frisk?" she only nodded Scarlet took off her jacket and straightened out her black top. She placed her jacket over Frisk's shoulders who seemed shocked at first but smiled at her.

"Thanks" Scarlet smiled and just shrugged. "I have a question" she turned to her as to show attention to her question. "How are you talking? I mean you don't have a bottom jaw" Scarlet smiled.

"well you see most people know this but I guess your not used to it I have made sure to always talk through telepathy" Firsk nodded. "okay now I have a question how did you get here in the first place?" Firsk then went into a long story about their life on the surface and everything they have already been through before getting here. Scarlet was still quite questionable about humans only because of her first encounter with one but this one seemed different, different as in she felt connected to her more then a friend but a different connection than she has with her brothers. The two talked for at least an hour telling each other about their lives, apart from Scarlet's wildside, until Scarlet knew that she'd have to leave and get back home to make sure Sans was awake. Bu before she left she turned round to Frisk smiling and saying. "Hey be safe Frisk. I'll see ya 'round" Frisk smiled and waved as Scarlet teleported back to the house, checking the bedrooms and even the lab Scarlet was surprised to see no one was home. Scarlet waited a few hours before Papyrus came home with Frisk saying how they had battled and Frisk said they wanted to be his friend. A few hours passed and Frisk had to set off to get to the barrier it saddened Scarlet that her friend had to go and Sans knew this so after the kid left Sans walked up to Scarlet saying.

"why don't ya go and meet her?" Scarlet looked to Sans, a surprised look on her face.

"W-what do you mean?" Sans smiled at her.

"When I meet them at the judgement hall go with them after that they will need the encourgement" She smiled and hugged her brother who hugged her back. "But please promise me you'll be safe" She promised and ran upstairs and waited for her brother to come and get her. As the hours ticked by Scarlet became worried and bored. Bored because of the fact that she was just waiting but worried because if Frisk didn't get to the hall that meant that they had been... No. She couldn't think like that she would see her at the hall. A few minutes passed and Sans walked in telling her it was time she held his hand and they teleported to the hall where Sans gave Frisk his speech and when he left Scarlet moved in.

"Hey Frisk" Frisk smiled even more than she was when she saw Sans.

"Scarlet what are you doing here?" Scarlet shrugged.

"I figured ya might want some encourgement" Frisk smiled and nodded.

"That'll be nice"


	9. Chapter 9

Soon the duo came to the throne room Scarlet turned to Frisk who looked scared and nervous at the same time Scarlet was about to say something when she heard a noise from the soul room.

"Frisk you go ahead I need to check something" Frisk nodded and Scarlet went into the room. Nothing seemed out of placed but then she noticed that there was small cracks on the containers.

"Well hello Trashbag Jr." Scarlet spun around and saw Flowey who had a dark expression on his face. "I always figured that you would befriend the little brat but for you to feel something other than friendship! hahahahh!" Scarlet tried to hide a blush as she glared at him.

"What do you want weed?!" He smiled at her.

"I want the souls to become a god but I think I'll need something to weaken the human mentally. Maybe you!" Vines suddenly shot at Scarlet which she dodged blocking some with bones but they kept firing at her. After blocking some attacks she was suddenly grabbed by a vine holding her up Flowey laughed and shot vines at the souls making them go around him. "IT'S SHOWTIME!" he used his powers to take them to the throne room where Asgore was on his knees in front of Frisk who was refusing to kill him. Suddenly Flowey fired pellets at Asgore and even though Scarlet didn't like him no one should be killed like that or any other way. Flowey appeared in front of Frisk laughing. "In this world it's kill or be killed you idiot! But first I have a surprie for you" He then threw Scarlet to the ground in front of Frisk, Scarlet weakly stood up but as she finally got to her feet she felt a sharp pain stab through her making her gasp for air. Looking from Frisk's destrought face to her chest she saw that Flowey had sent a sharp vine through her chest her neon blue blood falling down her chest and dripping onto the floor. Scarlet could feel herself getting weaker as she looked at her hand which was turning to dust as was the rest of her body. Before she dissapeard she smiled at Frisk and waved goodbye.

Frisk slumped to her knees crying into her hands barely able to look at the pile of dust as Flowey laughed. Suddenly a golden glow caught both the human's and the flower's attention as something came out of the dust. A small golden object erupted from the dust and went straight to Frisk hovering in front of her was a small golden heart. It was Scarlet's soul.

"Impossible! no monster could still have a soul after it dies!" Frisk cupped the soul as it went closer. "No matter it will be mine!" A vine shot at Frisk but she held the soul close the her and a sudden jolt of power ran through her. As she opened her eyes she saw a large bone was in front of them blocking the vine Flowey glared as Frisk closed thier eyes and when they opened them one of their eyes was red as blood. Flowey abosrobed the souls and transformed into Omega Flowey sending mutiple attacks that Frisk either deflected or dodged witht the help of Scarlet. Soon the human souls fought against Flowey taking him down making him scream in pain. A blinding light made Frisk cover their eyes and when the light was gone a damaged Flowey was in front of them. Even then Frisk refuesed to kill Flowey even after the weed threatened to kill everyone she loved. He then left whimpering. "I don't understand". Frisk left with Scarlet's soul and went back to the surface where she began her life again but after a few weeks her phone rang. Scarlet's powers light up indicating that she was listening, the monsters each talked to Frisk saying about how the Underground changed but as they the call came to an end Sans said.

"By the way kid if you know what happened to Scarlet let us know. I have my theorys but I hope to God that it's not true, cause when the guards entered the throne room they found Asgore's ashs but I found something they didn't. I found a very little amount of different ashs" Sans went silent on the other end for a minute. "Anyway the phones about to die so we'll see ya 'round kid" After Frisk hung up she felt Scarlet's powers shut off which rarely happened she would useuly stay or fade away. Flowey suddenly popped up offering Frisk a better ending if they go back in the save files and it will also bring back Scarlet cause it will be before she died. Frisk looked to a large glowing button that read 'Reset Save File' hovering their hand over it she pressed down firmly on it.


	10. Chapter 10

Scarlet was covered in a blinding light before she opened her eyes again seeing that she was laying on her bed sitting up she looked at the clock that was on the other side of the room. It was a few minutes before she was to meet Frisk at the Judgement hall jumping up she ran outside her room to bump into Sans who looked shocked to see her running out her room.

"heh, you must be really eagar to see the kid huh?" Scarlet just nodded and smiled. "Well let's go then" They went through the conversation with Sans again but when he left and Scarlet walked foreward Frisk lundged wrapping their arms around Scarlet. Scarlet wrapped her arms around Frisk hugging her tightly. Frisk was now crying as she whimpered out.

"I thought I had lost you Scarlet, I don't want to lose you" Scarlet smiled and hugged Frisk tighter.

"Don't worry you won't lose me" Scarlet let go of Frisk and looked at her more serious. "But we do need a plan cause no doubt the weed has other plans" Frisk thought for a moment before saying.

"Wait I've got a plan" After the plan was said Scarlet and Frisk did what they did last run meaning Scarlet walked towards the soul room. But as she walked off Frisk grabbed her hand saying. "Scarlet I know we have the plan but what do I do if you do...?" Scarlet didn't even need Frisk to finish before she knew what she meant.

"If anything bad does happen do what you did in the last run. I'll still be alive just in a different form" Scarlet looked towards the soul room but looked back saying. "By the way I'll need to have a conversation about my soul after this" Scarlet then set off to the room where Flowey was after the same moves she allowed the vine to grab her and take them to the throne room. But this time Scarlet could see her brothers and all of their friends there but they had been grabbed by Flowey. The said flower then popped in front of Frisk laughinh.

"I think you know what else I have up my sleave" He then threw Scarlet towards the ground but this time as the vine headed towards her she summoned a bone to block the attack. "W-what? How could you-?" Scarlet stood next to Frisk igniting her eye she turned to Frisk.

"Frisk stand back. This won't take long" Scarlet summoned multiple bones and Flowey summoned multiple pellets which each fired. However after many shots were fired Flowey growled in annoyance.

"ENOUGH!" Two small vines grabbed Scarlet's wrists before a large vine stabbed into Scarlet's chest pinning her into the wall. Scarlet could hear her brothers shouting her name in worry. Scarlet placed a weak hand on the vine grunting in pain she looked to Frisk saying.

"Well, looks like it's plan B, huh?" Scarlet new what would happen but it still hurt like hell. As she turned to dust all the monsters, apart from Flowey, were shocked to see that Flowey had so eaisly killed a child. The golden heart appeared yet again this time it zipped past Flowey's head slightly tearing his petal. It then floated next to Frisk circeling her one. Frisk gently cupped her hands underneath the soul before looking up at Sans and Papyrus who both nodded knowing what Frisk was asking. Frisk pressed the soul into her and again Scarlet's powers flared up one of Frisk's eyes glowing red. What happened next shocked everyone except Frisk. "Ya never learn do ya weed?" Scarlet's voice came from Frisk as if she was in control she pointed a hand foreward and readied a shot when Flowey encircled the two with sharp pellets.

"DIE ALREADY!" the pellets hit them multiple times Frisk slumped to their knees gasping for air. Scarlet tried to use her magic but Flowey would block or stop her. Suddenly when a pellet fired it got blocked by each of the monsters soon they recovered their health and all of Frisk's new friends were in the room but then Flowey smiled evily. "You Idiots! ALL YOUR SOULS ARE MINE!" A blinding light made the duo to cover their eyes and stood in front of them was a small goat child. He spoke to them but the beginning of the scentence was mumbled. "Are you there? It's me your best friend, Asreil Dreemur"


	11. Chapter 11

The small goat child suddenly turned into a bigger version wearing a tunic with the Underground symbol he laughed as he pulled out two giant swords. He swung them at Frisk who dodged until he fired a gun at her making it unable for her to dodge but as the bullets aimed to Frisk Scarlet released a Gaster Blaster disintergrating the bullets. After several attacks Asreil growled in annoyance and said.

"very well looks like I'll have to use all of my power to eliminate you" Suddenly Frisk could feel everything around her being sucked foreward towards a large black hole like object. Suddenly Asreil had turned into a giant god like demon known as Asreil Dreemur God of Hyperdeath. The darkness around Frisk wrapped around her making her unable to move Asreil laughed but Frisk could sense something inside Asreil.

"Frisk it's the souls we have to do something" Scarlet said to Frisk. Using her determantion Frisk was able to summon all of her friends to 'Save' thier souls. Scarlet helped as best as she could but used all of her magic with her brothers almost crying when she saw them with their faces blurred unable to remember anyone. Scarlet wouldn't let Frisk know but everytime she helped using her powers she would begin to feel weaker and weaker. But they had soon helped all of their friends but Frisk could sense she could save another soul. Reaching out Frisk walked towards Asreil who looked at her surprised.

"W-what are you doing?" Frisk didn't stop as she kept walking foreward. "N-no I don't need anyone" He growled. "Do you know why I am trying so hard to keep you here? It's cause i care about you. Your the only one who understands me. SO JUST LET ME WIN!" He then fired a large shot which hit Frisk but she wouldn't die. In a sudden blinding light the child version of Asreil was stood there crying. "I was always a crybaby" After a breif introduction Scarlet moved back in Frisk's body letting them have a moment when Asreil used the human and monster souls to break the barrier. He then was given a hug from Frisk and left back to the ruins. Frisk suddenly woke up but by now Scarlet was feeling even weaker in her transparent form in Frisk's mind she couldn't even stand up. When Frisk looked around she saw all of her friends around her but she wasn't worried about her health she quickly ran to Sans and Papyrus saying.

"Scarlet's feeling really weak" Sans and Papyrus looked at each other in worry when Sans said.

"Let's have a look at her soul" Using her powers Scarlet allowed Frisk to hold her soul in her hand and what they saw was not good. Scarlet's soul was turning black from the centre and cracks of grey were forming. "this isn't good i think her souls dying I guess it can only be out of an original form for so long before the soul follows suit with the body" Frisk began crying at this news all that was left of Scarlet's body was a pile of dust cupping the soul in her hands Frisk kneeled down and cried hugging the soul. Suddenly a red aura surronded Frisk and trailed off her like a tail connecting to Scarlet's soul and the pile of dust. Everyone was in awe except Frisk who hadn't noticed until Sans said. "Kid how are you doin' this?" Looking up the red aura was know surronding the dust pile and the soul was getting more golden. In one movement the soul had turned back to normal and had zipped back to the dust pile which was shifting. The dust began to form a shape and after a few moments Scarlet was back to normal she was slightly weak but she was back. As the aura dissapeard Scarlet began to fall over but Papyrus caught her picking her up.

"What did I just do?" Sans shrugged.

"I honestly don't know kid but whatever you did I'm glad you did it"


	12. Chapter 12

Scarlet had been asleep for a few hours now but her soul was back to normal so no one was worried she would just have to wake up in her own time. Frisk insisted to be next to her which everyone allowed so when Sans and Papyrus were given a new home above ground Toriel had allowed Frisk to sleep at their house that night. Scarlet had been placed in a bare room that she could decorate when she was awake Frisk had placed a blanket on the floor and a pillow and slept next to the mattress that Scarlet was asleep on. However when Frisk had fallen asleep Sans walked into the room and placed her next to Scarlet on the mattress and left the room. Later that night Scarlet began to stir and when she opened her eyes she became confused but when she turned her head to the side her eye sockets went wide and a dark red blush creeped across her face. Frisk instead of moving away snuggled closer to Scarlet who was shocked at first but eventually hugged Frisk and fell back asleep. The next morning Sans woke the two up for breakfast and when he saw them he smiled as the two were asleep hugging each other protectively. After the two had eaten breakfast Scarlet went to work decorating her bedroom she firstly found her stuff from downstairs and put the furniture in her room. This consisted of a bed a wardrobe and a chair and table. But in the bottom of a box she found two things she hadn't seen in years the first was a picture of her father with her and her brothers. After the accident Sans and Scarlet told Papyrus that their father had gone away to help the king and wouldn't be back for a long time. She placed that in her pocket and the other thing was a small blue ukulele that Sans had given her. Frisk was bringing up a box of her clothes when she saw the instrument and asked.

"Hey I didn't know you could play Scarlet" Scarlet smiled looking to Frisk she said.

"yeah I did ages ago I used to love playing all kinds of instruments but then..." Scarlet trailed off and sighed before smiling again. Frisk thought for a minute before saying.

"Can I hear some?" Scarlet was surprised.

"What?"

"Can I hear some of your music? I'm sure I'll love it" Scarlet seemed hesitant at first but then played a few short songs which Frisk loved and even clapped at the end of each one of them. This made Scarlet blush deeply and even Frisk had to hide a blush that was forming on her cheeks they both looked away from each other and composed themselves before they carried on setting up the room.

Seven years had passes since Frisk had freed everyone and her and Scarlet had only gotten closer and closer. Sans had already gathered that Scarlet had feelings towards Frisk but so did Mettaton and even Toriel had gather from Frisk's behaviour when she was around Scarlet. On this day Scarlet was laid on her bed tuning her uklelale and writing down notes and lyrics to her newest song that she had been writing. Just as she had finished writing another line of the song her phone vibrated.

 **'hey Scarlet it's Frisk. Do you wanna meet up?'** Scarlet unlocked her phone and answerd back.

 **'sure where do you wanna meet up?'**

 **'how about the cliff where the barrier was broken?'** Scarlet replied agreeing to meet up there. When she got to the mountain top Scarlet saw Frisk with her legs dangling over the edge. Scarlet walked over to Frisk and sat next to her staring out into the distant sunset.

"It's a great view isn't it?" Frisk asked Scarlet.

"yeah it's really beautiful" they sat there in silence until Frisk sighed and spoke.

"Scarlet there is something I should tell you" this made said skeleton look at Frisk. "For a while now I've had feelings to you. I never knew how you felt but I couldn't hide these feelings anymore. I will understand if you don't feel the same way that I d-" Frisk was suddenly cut off by Scarlet "kissing" her (A/N I DON'T KNOW WHAT CLASSES AS A KISS FROM A SKELETON) Frisk and Scarlet blushed deeply before leaning further into the kiss. After a few seconds they let go and just looked into each other's eyes.

"I love you to Frisk"


	13. Chapter 13

It has been five weeks since Scarlet and Frisk had confessed their love to each other all of Frisk and Scarlet's friends and family had been told and everything was going great. But then on one fateful day Scarlet had just hung up the phone after talking for an hour to Frisk about dinner plans they were having that night. She then decided to go to take a nap before getting ready but as she fell asleep she felt a surge of energy go through her and when she woke up she looked out the window and saw that she was back in Snowdin and she was back to being seven years old. Scarlet felt hurt and betrayed, had Frisk reset because she didn't like Scarlet anymore? Had Scarlet done something wrong to Frisk? Scarlet got out of bed and went to talk to Sans but when she stepped out of the door she saw that it was night time because there were no lights on in the house. She decided that she would get a drink before heading to Sans room to see if he was there when she heard Papyrus's voice from downstairs.

"HUMAN I KNOW YOU ARE EXCITED FOR OUR BATTLE TOMORROW BUT I DON'T THINK YOU NEED YOUR WEAPON NOW" Scarlet's heart skipped a beat when she heard Papyrus grunt in pain and looking through the banister on the stairs she saw the horrifying sight of her elder brother turning to dust. But what was hurting her heart more was the fact that it was Frisk that was holding the knife. Suddenly there was the sound of the wind in the house and Sans was stood there glaring at Frisk saying.

"You shouldn't have done that. You dirty brother killer!" Sans had managed to get a few good hits but Frisk's eyes landed on Scarlet and the sight made Scarlet freeze Frisk's once sparkling brown eyes were now blood red. Frisk charged at Scarlet and slashed but before a hit could land Sans was there blocking the hit. Frisk saw this and laughed before running out of the door leaving Scarlet clinging to Sans who placed a weak hand on her back as she cried. "hey don't cry Scarlet it's gonna be okay. Everything's... g-gonna b-be fine..." his last sentence staggering as he turned into dust in Scarlet's hands. All she could do was cry she had now lost her brother's three times but as she cried the red fire in her eye began to ignite soon becoming an unstoppable inferno. She then grabbed Sans jacket and wrapped Papyrus's scarf around her small neck. Still glaring she teleported to the judgement hall this place once filled with happy memories for Scarlet and Frisk now was going to be a battle ground where Scarlet would have to kill the one she had loved. Just then Scarlet heard footsteps in front of her and she sighed okay it was now or never.

 **"A pleasant breeze flows by leaving a trail of dust**  
 **This is your fault, right?**

 **Standing in the corridor**  
 **Who thought we'd be here like this together?**  
 **On a gorgeous day like this, I ask**  
 **What is it that you want?**

 **I believe there was a time**  
 **Where we could be pals and things were better**  
 **Eating bad food, enjoying laughs**  
 **Can we go back to that?**

 **If you're in there listening, kid,**  
 **Just reset the time line and**  
 **Let's please forget all of this**

 **Even after what you did he believed in you**  
 **'til the end.**

 **Looking at your face right now**  
 **That expression tells me I can't**  
 **Afford not to care anymore**

 **Turn this path around, wipe your dirty hands clean.**  
 **Give up!**

 **Please don't come back**  
 **If you're my friend**

 **Please..**

 **Listen and hear a song the birds are singing**  
 **Sit down a while and watch the flowers blooming**  
 **A pleasant breeze flows by leaving a trail of – (dust)**  
 **How could you have done this?**

 **Is there still**  
 **A glimmer of hope?**  
 **Will you choose**  
 **To do the right thing?**

 **Please now, bud**  
 **If you're there**  
 **Have a change of heart**

 **Listen and hear a song the birds are singing**  
 **Sit down a while and watch the flowers blooming**  
 **What a nice day.."**

Scarlet had sent multiple attacks towards Frisk but each one she dodged or managed to hit away with her knife. Soon after using so much magic she slumped to her knees in a weakened state. A shadow loomed over Scarlet and when she looked up she saw Frisk smiling evilly at her, Frisk then raised her knife and prepared to kill Scarlet who closed her eyes. The knife swung down but it never hit Scarlet as when the knife came within a few centimetres away from her another Frisk appeared in front of the knife. This Frisk was the one that Scarlet had come to know and love but now tears were falling down her face and a trickle of blood fell from the corner of her mouth. Frisk fell forward and Scarlet quickly caught her placing her down she rested Frisk's head on her lap and as Frisk's pulse began to slow down she coughed out.

"Scarlet take my soul and undo Chara's doing" Frisk then shut her eyes and a red heart appeared which the other Frisk, now know as Chara, had sprung for. Scarlet quickly grabbed the soul and absorbed it. Opening her eyes both were ablaze, the red colour brighter then ever before Chara smiled and prepared the strike when Scarlet threw her hand up impaling her with a jagged bone. She then surrounded Chara with Gaster blasters and fired incinerating her to dust.

"That was for my brothers, you Megalomaniac" Scarlet then sighed. "Okay Frisk let's reset and go back home" Scarlet used a large energy and reset the timeline and when she opened her eyes again she was back on the surface and back to her normal age.


End file.
